Alkaline cylindrical dry cell



Feb. 20, 1951 s. RUBEN ALKALINE CYLINDRICAL DRY Filed Oct. 15, 1947CONNUNO n 1 NS. l,

area-14% 16 /Mrdavfoe/ ,ilrromvEY Patented Feb. 20, 1951 i UNITED STATESPATENT `OFFICE ALKALINE CYLINDRICAL DRY CELL Samuel Ruben, New Rochelle,N. Y.

Application October 15, 1947, Serial No. 779,874

14 Claims. 1

This invention relates to primary cells, and, more particularly, to anovel andv improved electrode assembly for alkaline dry cells.

In my U. S` Patent 2,422,045, dated June 10, 1947, relating to analkaline dry cell, there is disclosed a sealed alkaline primary cellhaving an amalgamated zinc anode, a cathode formed of a conductive bodycontaining an electrolytically reducible oxygen-yielding compound (suchas mercurio or silver oxide) and an immobilized electrolyte comprisingan aqueous solution of an alkali metal hydroxide (such as potassiumhydroxide) containing a substantial quantity of alkali metal zincate.The presence of the zincate in the electrolyte, in combination withother features described in the said patent, prevents or stronglyinhibits any tendency for a chemical hydrogengenerating reaction to takeplace between the electrolyte and the zinc anode when the cell is storedprior to use as well as during active use. These factors have madepossible a sealed alkaline dry cell which does not generate substantialgas or leak electrolyte during shelf life or when 1n use.

In my co-pending applications Serial No. 674,588, led June 5, 1946, andSerial No. 682,734, filed July 11, 1946, I have disclosed alkaline drycells of the general type described in my aforesaid patent and moreparticularly cylindrical cells of the so-called penlight type comprisingan amalgamated zinc anode, a, cathode-depolarizer body pressed on a rodof ferrous metal, and a body of alkaline electrolyte gel interposedbetween and in Contact with the said anode and cathode. Preferably, thezinc anode is surrounded by and is in contact with a cell containerformed of a metal inert to the electrolyte and having a low contactpotential to zinc. The quantity of zinc in the anode is balanced withthe depolarizing capacity of the cathode so that both anode and cathodeare consumed substantially simultaneously. When such a cell combinationis used with an alkaline electrolyte, it makes possible the provision ofa sealed alkaline dry cell which is free of any tendency to eectrolyteleakage or gas generation during shelf life. current generating life andat end of life, Such a cell can safely be used in any sort of eguipmentwithout hazard or damage due to electrolyte leakage or celldisintegration, even if the cell is allowed to remain in the equipmentlong after the end of its useful life.

The present application relates to a primary cell which constitutes animprovement over the cells disclosed and' claimed in my aforesaidcopending applications.

(Cl. 13S-107) In prior alkaline cells of the cylindrical or penlighttype, the cathode assembly generally comprised a rod of ferrous metalhaving pressed thereon a generally cylindrical coherent conductive bodycontaining an electrolytically reducible oxygen-yielding compound (suchas mercurio oxide), usually having nely divided inert material of higherconductivity (such as micronized graphite) intimately mixed therewith.While cathode assemblies of this type provided excellent results inalkaline dry cells of the described character, certain difficulties wereexperienced when manufacturing the cells on a quantity production scale.Frequently, cracks or ssures would develop in the pressed depolarizerbody shortly after assembly of the cell. These cracks or fissures wouldfrequently be accompanied with localized crumbling or breaking up of thecathode-depolarizer body and adversely influenced both the shelf as Wellas the useful life of the cell. Also, these changes in the shape andcoherence of the cathode body had a detrimental influence on theelectrical contact between the cathode body and its supporting orterminal rod.

After a careful experimental investigation of the outstanding problem,it was found that the foregoing difficulties were caused by expansion ofthe cathode body. Upon introduction of the cathode structure into thecell, electrolyte will be absorbed by the cathode causing expansion orswelling thereof. This expansion or swelling will cause a slightdisplacement or slipping of the cathode body on the supporting rod andwill substantially increase the contact resistance therebetween.Moreover, since the supporting rod is non-compressible, the resultingstresses will be tran'sferred to the exterior cylindrical surface of thecathode and will result in the production of cracks or ilssures,generally extending in an axial direction.

I have discovered that the outstanding problem may be solved in a simplemanner.

It is an object of the present invention to provide an electrodeassembly for primary cells which eliminates the diniculties andinconveniences experienced in connection with prior electrodestructures..

It is another object of the invention to provide a novel and improvedcathode assembly for primary cells, specically for alkaline dry cellshaving a cylindrical construction.

The invention also contemplates a sealed alkaline primary cellcomprising a cathode assemblyV in which' the expansion or swelling ofthe cathode body is compensated for and the occurrence of 3 d cracks andfissures in the compressed cathode body is positively prevented.

Other and further objects and advantages of the. present invention willbecome apparent from the following description, taken in conjunctionwith the accompanying drawing, in which Fig. 1 is a longitudinal sectionthrough an alkaline dry cell embodying features of the presentinvention; and

Fig. 2 is a transverse section taken on line 2-2 of Fig. 1.

Broadly stated, according to the principles of the invention, thecathode is provided in tbe form of one or more generally cylindricalpressed coherent bodies containing an electrolytically reducibleoxygen-yielding compound which is preferably intimately mixed with afinely divided inert material of higher conductivity. An axial channelis provided in each of the cathode bodies through which a supporting rodof an inert metal, such as a suitable ferrous metal, may extend in a.loosely tting relation. This relation is assured by making the diameterof the supporting rod smaller than that of the channel in said bodies.Electrical and mechanical connection between the cathode rod and thecathode body or bodies is provided by means of apertured metal end capsor washers of which one is force-fitted on each terminal region of therod so as to assure pressure contact with the respectvie end faces ofthe cathode bodies and to maintain the said boies -under compression atall times. In this manner, a good electrical contact is permanentlyassured between the cathode bodies and the supporting rod, the saidcontact of low electrical resistance being improved rather thanadversely affected by expansion or swelling of the cathode bodies. Also,since the diameter of the channels in the cathode bodies is greater thanthat of the supporting rod, expansion or swelling of the said bodiesupon absorption of the electrolyte will not result in cracks or fissuresand the cathode bodies will retain their initial shape throughout theuseful life of the cell.

Referring now more particularly to the drawing, reference numeral IIJdenotes a cylindrical containerformed of a metal inert to theelectrolyte and having a low contact potential with respect to zinc,when amalgamated, such as copper or silver, or alloys thereof with othermetals,

the preferred material being commercial bronze, which is an alloy of 90%copper and 10% zinc. Container I is closed at one end and is amalgamatedon itsinner surface. Within container I0 there is provided a corrugatedand perforated zinc anode Il of the type disclosed in my aforesaidco-pending application Serial No. 682,734, which is likewiseamalgamated. In place of corrugations, it is possible to deform theanode in other ways, such as by embossing, in order to provide anadequate area. It will be noted that anode I I has a substantiallygreater surface area than container I0 and is in electrical contact withthe inner surface of the container, the said contact being assured andimproved by an amalgam bond between container and anode.

The cathode assembly comprises a pair of cy lindrical pressed coherentbodies I2 formed of an electrolytically reducible oxygen-yieldingcompound (for example, mercuric oxide) which may have a smaller quantityof finely divided inert bly of two. Whether the cathode is made of oneor several pieces depends upon the convenience of manufacture and isprincipally determined by the dimensions of the cell'. An axial channelI3 of circular cross section is provided in'cathode bodies I2 throughwhich extends a supporting rod I4 of similar cross section formed of ametal inert to the electrolyte and to the cathode materials. This may bea suitable ferrous metal, such as steel, and when silver oxide isemployed as the depolarizer, the rod is silver plated. The diameter ofrod Il is preferably smaller than that of channel I3 in the cathodebodies. A pair of apertured end caps or washers I5 are forcetted on rodIl at the ends thereof in such a position as to be pressed against therespective end faces of the cathode bodies and to maintain the saidbodies under compression. As has been set forth in the foregoing, thisform of construction permanently assures a good electrical contact Y oflow resistance between the cathode bodies and their supporting rod.Also, as the result of the larger diameter of channels I3 as compared tothat of rod I4, space is provided to take up expension of the cathodebodies also in the radial direction, whereby cracking of said bodies andthe formation of fissures therein is positively prevented. End caps orwashers I5 may be formed of the same metal as rod I4. Both the end capsmaterial of higher conductivity, (for example and the supporting rod maybe silver plated for better surface contact with the cathode bodies, ifdesired.

The coaxial position of rod I4 within container I0 is assured by a pairof mica spacers I6 of triangular shape, each having an opening Il in thecenter thereof through which the said rod may pass. The top one of saidtriangular spacers is of such dimensions as to have its three pointsextend to the inner surface of can I0, while the dimensions of thebottom spacer may be slightly smaller to have its three points orterminal regions engage the inner surface of corrugated zinc anode II.The lower end of rod I4 rests on a mica disc IB provided at the bottomof container or can III. The upper end of the said rod is provided witha portion I9 of smaller diameter constituting the cathode terminal ofthe cell. A shoulder 2|) is arranged between the terminal and the bodyportion of rod I4.

'I'he space between the cathode assembly and the container is filled outwith a body 2| of immobilized electrolyte. This is composed of anaqueous solution of an alkali metal hydroxide, such aspotassiumhydroxide, which is converted into a gel by addition ofasuitable gelling agent, suchv as sodium carboxymethyl cellulose, or acereal starch. Preferably, the gel electrolyte initially contains asubstantial quantity of alkali metal zincate, such as potassium zincate,sufiicient to reduce the open circuit reactivity to a negligible value.However, the invention also contemplates electrolytes which areinitially free of alkali metal zincate. The composition and thepreparation of the eelctrolyte will be described more fully hereinafterin connection with the assembly of the cell of the invention.

Before assembling the cell, the brass can I0 and the zinc anode memberII are separately amalgamated, for example by bringing them in surfacecontact with an acidiiied 3% mercuric nitrate solution at 55 C. for fiveminutes. After amalgamation, the can and anode member are washedand'dried. The can is amalgamated on the inside only, the amalgamatingsolution being poured into the can.

In assembling the cell, mica disc I8 is rst placed in the bottom of thecan I and corrugated zinc anode member II, bent into a cylinder, isforced into position over the disc, the corrugations pressing againstthe inside amalgamated wall of the brass can.

Electrolyte 2| comprises an aqueous alkaline solution immobilized as agel. The preferred electrolyte is formed of C. P. potassium hydroxide(88% KOH) grams 100 Zinc oxide do` 16 Water ml 100 This electrolyteisimmobilized with grams of sodium carboxy-methyl cellulose per 100millilitres of the alkali zincate solution. In making the electrolytethe potassium hydroxide is added t0 25 millilitres of water and the zincoxide added. This mixture is stirred and heated to 180-190" C. and thenallowed to cool to 110 C., after which 25 ml. of water is added, a clearsolution being obtained. The sodium carboxy-methyl cellulose is crushedand screened through a 40 mesh screen and is added slowly to thesolution, with constant stirring to form an emulsion or paste typesubstance. This is forced by extrusion from a tube into the cell whichis heated to at least 100 C. and preferably to a temperature of about120 C. At this temperature a clear fluid is obtained which upon coolingis converted into a tough. adherent, water-clear gel of low electricalresistance. When the electrolyte in the cell is at 120 C., the cathodeassembly comprising supporting rod I4, cathode bodies I2 and end caps I5is pushed in. The electrolyte rises around the said assembly and uponcooling congeals to an adherent gel surface. The gel fllls all freespaces between the cathode assembly and the can and covers both sides ofanode member I I.

After the electrolyte gel is solidified by cooling to room temperature,a layer 22 of heated petroleum jelly, mixed with about 50% of ahydrocarbon polymer known in the trade as Vistinex for better adhesion,is poured on top of the surface of electrolyte gel body 2I, in order toseal it from the atmosphere. An oil-impregnated absorbent paper disc 23is placed on top of the layer of the adhesive petroleum jelly. To effectan air-tight seal of the cell a laminated disc or coverplate 211 isprovided, composed of an insulative disc 25 about Blf thick whichv iscoated on both faces thereof with a layer 26 of a synthetic elastomerknown in the trade under the name neoprene, having a thickness of about1/64". Disc 25 has a central aperture 2l therein through which extendsthe upper end I9 of steel rod I4, having a reduced cross section.Thereafter, the upper edges of container I0 are crimped down upon disc25, as shown at 28. This will press the center portion of disc 25against shoulder 20 of steel rod I4 so that a complete and air-tightseal is obtained.

If during operation of the cell gas is generated, the increase ininternal pressure will cause slight upward bulging of the coated disc 25which allows some venting to occur in the region between shoulder 20 ofrod I4 and the bottom surface of disc 25. Thus, the cell is protectedfrom the development of excessive internal pressures in a simple,inexpensive and highly efficient manner.

While sodium carboxy-methyl cellulose is the pref .rred gel-formingagent, other materials may be used with equal or similar results. Theinvention also contemplates an electrolyte prepared in foregoing butwithout the ,incorporation 'of av gelforming agent. In that 'casethe'ele'ctrolyte is utilized in the liquid .formand is immobilizcd 1 bysuitable absorbent spacer materials, such as Dexter paper or illterpaper, interposed' between cathode cylinders I2 and anode Ii.

The physical dim-nsions ofA the cell are, of course, determined inaccordance with 4the capacity desired for a particular application.Thus, inv a practical cell embodying the invention, the can or containerI0 had an outer diameter of 0.530", aheight of 1%", and was formed ofcommercial bronze 8 mil thick. The anode member was 11/2 inches squareand was made by perforating a l5 mil zinc sheet with 325 holes of 33mils diameter per square inch, vand corrugating the sheet with IIcorrugations per inch to an overall thickness of 25 mils.. Cathodesupporting rod I4 was formed of steel and had a diameter of 0.125 and anoverall length of 1.910" with a portion of reduced cross section I9having a diameter of 0.098 and a length of 0.140. Cathode cylinders I 2had inner and outer diameters of 0.127 and 0.325", respectively, andwere 0.750" long each. They were formed of an intimate` mixture of about90% mercurio oxide and of about 10% micronized graphite compressed undera pressure of about 30,000 pounds per square inch. End caps I5 were inthe form of steel washers having an outer diameter of 0.320, an innerdiameter of 0.123 and a thickness of 0.020". The

v quantity of the electrolyte, having the composir mental inV reducingthe open circuit reactivity in the cell to a negligible value. This' isessential in order to assure a long shelf life for the cell at highstorage temperatures and is critically important in cells which arestored andv used in the tropics.

It is possible, however, to provide satisfactory sealed alkaline drycells comprising an electrolyte of substantially solid consistencyformed of an aqueous solution of an alkali m tal hydroxide in theabsence of zinc oxide, the said solution being immobilized by theaddition'of a small amount of sodium carboxy-methyl cellulose, orprocessed starch. Such electrolytes may be used with the cell structuresillustrated in this application as well as in cells including theelectrode structures disclosed in my Patent No. 2,422,045, or in any.one of my aforesaid co-pending applications. In

cells employing an electrolyte of solid consistency (that is a gelelectrolyte, or a solid crystalline electrolyte, such as is disclosed inmy co-pending application Serial No. 468,386, l d December 9, 1942, nowPatent No. 2,463,565, dated March 8, 1949) in the preparation of whichno zinc oxide is used, a saturated Zn(OH)2 content is vbuilt up in theboundary layer of the solid electrolyte and anode, and this tends tolimit internal reaction on shelf and cell gassing.

.Cells of the described character, in which the addition'of zinc oxideto the electrolyte of substantially solid consistency was dispensedwith,

anatre 7 are characterized by a reduced internal resistance and anincreased flash current, this being particularly accentuated when thecells are operated y at very low temperatures. Thus, in comparativetests, alkaline cells made with an electrolyte containing zinc oxide(100 parts by weight KOH, 16 parts ZnO and 100 parts H2O, with a smalladdition of sodium carboxy-methyl cellulose) gave an average flashcurrent of 1.0 ampere at f30 C., while Ruben cells of identicalconstruction but containing no zinc oxide in the electrolyte (100 partsby weight of KOH and 100 parts of H2O. with a small addition of sodiumcarboxy-methyl cellulose) gave an average ilash current of 2.0 amperesat the same low temp.rature. In other words, the omission of zinc oxidein electrolytes of generally solid consistency resulted in an increaseof 100% in flash current at low operating temperatures. Ad v As to thisfeature of th invention, the present application is acontinuation-impart of my aforesaid co-pending application Serial No.468,386, now Patent #2,463,565.

Although the present invention has been disclosed in connection with afew preferred embodi` ments thereof, variations and modifications may bersorted to by those skilled in the art without departing from theprinciples of the invention. I consider all of these variations andmodifications to be within the true spiriti and scope of the presentinvention, as disclosed in the foregoing description and defined by theappended claims.

What is claimed is:

1. A sealed alkaline primary cell comprising, in combination, at leastone generally cylindrical coherent conductive cathode body containing anelectrolytically reducible oxygen-yielding compound and having an axialchannel therethrough, a terminal rod of ferrous metal extending throughsaid channeland having a diameter which is smaller than that of thechannel, the inner surface of said channel deilning an expansion spacewith said rod for free radial expansion of said cathode body, anapertured metal contact plate force-fitted on each end of said rod inpressure engagement with the corresponding end face of said cathode bodythereby holding the said body under axial compression but radiallyspaced from the rod, an amalgamated zinc anode surrounding said cathode,an immobilized body of an alkaline velectrolyte interposed between andin contact ode so that both anode and cathode are consumed substantiallysimultaneously.

2. A sealed alkaline primary cell comprising, in combination, at leastone generally cylindrical coherent cathode body having an axial channeltherethrough and containing an electrolytically reducibleoxygen-yielding compound intimately mixed with finely divided conductingmaterial, a metal supporting rod extending through said channel andhaving a diameter smaller than that of the channel, the inner surface ofsaid channel defining an expansion space with said rod for free radialexpansion of said cathode body, an apertured metal contact plateforce-fitted on each end of said rod constructed and arranged to holdthe said cathode body under compression therebetween, an amalgamatedzinc anode surrounding said cathode, a body of alkaline electrolyte gelinterposed between and in contact with said cathode and anode. and acell container of inert metal of low potential to zinc surrounding saidzinc anode and in contact therewith.

3. A sealed alkaline primary cell comprising, in combination, at leastone `cylindrical cathodedepolarizer body having an axial recessextendingthroughout the length thereof and being composed of compressed particlesof an electrolytically reducible oxygen-yielding compound intimatelymixed with similar particles of inert material of higher conductivity,said body being of such character as to expand when absorbing anelectrolyte, a supporting rod of ferrous metal extending through therecess of said body having a Adiameter smaller than that of said recess,the inner surface of said recess dening an expansion space with said rodfor free radial expansion of said cathode-depolarizer body, an aperturedend cap of ferrous metal fixed on each end of said rod in such positionas to be in pressure contact with the end faces of saidcathode-depolarizer body whereby said body will be maintained under compression and in electrical conducting relation with said rod unaffectedby expansion of said body, an amalgamated zinc anode surrounding saidcathode-depolarizer, a body of electrolyte gel formed of an aqueoussolution of potassium hydroxide containing a substantial proportion ofpotassium zincate and being immobilized with sodium carboxy-methylcellulose interposed between and in contact with said cathode and anode,and a cell container of inert metal of low potential to zinc surroundingsaid zinc anode and in contact therewith.

4. A cathode subassembly for electrical current producing cells.comprising i-n combination, a cathode terminal rod, a cathode formed ofa coherent conductive body containing an electrolytically reducibleoxygen-yielding compound which will expand upon the absorption of anelectrolyte and having an opening therein through which the saidterminal rod extends, said opening having a diameter larger than that ofsaid rod by an amount greater than the maximum radial expansion of saidbody thereby providing an interspace for accommodating such radialexpansion,

and an apertured contact member fixed on each end region of said rodholding the said cathode body under compression therebetween and inelectrical conducting relation with the rod.

5. A cathode subassembly for primary cells comprising, in combination, acathode terminal' rod, a cathode constituted by an elongated coherentconductive body containing an electrolytically reducible oxygen-yieldingcompound which will expand upon absorption of an electrolyte and havinga generally axial channel therein through which said terminal rodextends, the inner diameter of said channel being larger than the outerdiameter of said rod by an amount greater than the maximum radialexpansion of said cathode body thereby providing an interspace foraccommodating such radial expansion, and an apertured contact plateforce-fitted on each end region of said rod holding the said cathodebody under compression therebetween and in electrical conductingrelation with the rod.

6. A cathode-depolarizer element for primary cells comprising, incombination, at least one generally cylindrical coherent conductive bodycontaining an electrically reducible oxygen-yielding compound which willexpand upon absorption of an electrolyte and having an axial channeltherethrough, a metal supporting rod extending which is smaller .thanthat/ofthe channel -by an amount `greater than" the maximumradial'expansion ofsaid conductivebodythereby providingan interspace foraccommodating such ifadial'expansion',` and an apertured metal contact`plate force- 1 thmughfsaidj channel analisi/'ing .a diameter fcornbin'atiori,I

.,wnstituted by an elongated coherenreonducuve body 'containing fanelectrolyticallyfreduciblel v` I oxygen-yielding compound whichwillexpand, up-

' cells comprising, in combination, a plurality of generally cylindricalcoherent bodies, each having an axial channel therethrough andcontaining an electrolytically reducible oxygen-yielding compoundintimately mixed with nely divided conducting material which will expandupon absorption of an electrolyte, a metal supporting rod extendingthrough the channel of each cylindrical body and havinga diametersmaller than that of said channels by an amount greater than the maximumradial expansion of said bodies thereby providing an interspace foraccommodating such radial expansion, and an apertured metal contactplate force-tted on each end of said rod constructed and arranged tohold said cylindrical bodies under compression therebetween and inpermanent electrical conducting relation with each other and with therod.

8. A cathode-depolarizer element for primary cells comprising, incombination, at least one cylindrical cathode-depolarizer body having anaxial recess extending throughout the length thereof and being composedof compressed particles of an electrolytically reducible oxygen-yieldingcompound intimately mixed with similar particles of inert material ofhigher conductivity, said body being of such character as toA expandwhen absorbing an electrolyte, a steel supporting rod extending through.the recess of said body and having a diameter smaller than that ofsaiclrecess by an amount greaterl than the maximum radial expansion ofsaid cathode-depolarizer body thereby providing *an interspace foraccommodating such radial expansion, and an apertured end cap of metalinert to said cathode-depolarizer and to said electrolyte fixed on eachend of said rod in such position as to be in pressure contact with theend faces of said cathode-depolarizer body whereby said body will bemaintained under compression and in permanent electrical conductingrelation with said rod unaffected by expansion of said body anddeterioration and cracking of said body during such expansion ispositively prevented.

9. An electrical current producing cell comprising, in combination, acathode terminal rod. a cathode formed of a coherent conductive bodycontaining an electrolytically reducible oxygenyielding compound whichwill expand upon absorption of an electrolyte and having an openingtherein through which said rod extends, the diameter of said openingbeing larger than that of said rod by an amount greater than the maximumradial expansion of said cathode body thereby providing an interspacefor accommodating such radial expansion, an apertured metal contact capxed on each end of said rod holding said body under compression on andelectrically connected with said rod, an anode surrounding said cathode,and an electrolyte body interposed between and in contact with saidcathode and anode.

`1.0. An alkaline primary cell comprising, in

y `on vabsorption of anelectrolyte and hayinga gene'rallyv axialchannelj therein through whichfsaid terminal rod extends, the diameterof said chanvnel being larger than that of said vrod by, an

amount greater than the maximum lradial expan- Y' sion of said cathodebody thereby providing an interspace for accommodating such radialexpansion, an apertured metal contact plate forcetted on each end ofsaid rod holding said cath-V ode body under axial compression on andelectrically connected with said rodbut radially spaced from the rod, anamalgamated zinc anode surrounding said cathode, and an immobilized'body of an alkaline electrolyteinterposed between and in contact withsaid cathode and anode.

11. A primary cell comprising a container; an anode, an electrolyte, anda cathode-depolarizer in said container;A said cathode-depolarizercomprising a metal rod, an apertured compressed body of depolarizermaterial having the property oi swelling and expanding in said celluponthe absorption of electrolyte, said Vrod extending through theaperture of Vsaid body and having a diameter smaller than that of saidaperture by an amount greater than the maximum radial expansion of saidcathode-depolarizer body thereby providing an interspace foraccommodating such radial expansion during cell life without cracking ofthe body, and an end contact member on each end of said rod in pressurecontact with the corresponding ends of said cathode-depolarizer bodythroughout cell life. Y

12. In a primary cell of the class wherein an immobilized electrolytecooperates with a zinc anode and with a cathode formed of a coherentconductive body containing an electrolytically reducible oxygen-yieldingcompound which will expand upon absorbing-said electrolyte, thecombination with said cathode body -of a metal terminal rod extendingthrough an opening in saidI body, the diameter of said opening beinglarger than that of said rod byl an amount'greater than the maximumradial expansion of s aid body therexed on each end of said rodAholding'said body conducting relation with the rod.-

13. In a primary cell of the -class wherein an immobilized alkalineelectrolyte cooperates with an amalgamated zinc anode and with a cathodeformed of a coherent conductive body containing an electrolyticallyreducible oxygen-yielding compound which will expand when absorbing saidunder compression therebetween-and in electrical electrolyte, thecombination with said cathode.

body of a supporting rod extending through a generally axial channel insaid body,fthe diameter of said rod being smaller than that of saidchannel by an amount greater thanV the maximum.

comprises an amalgamated zinc anode, a cathodea'r'eathqd'e,terminal'rod, a cathode gel interposed between and incontact with said anode and cathode, and a substantially air-tightenclosure for the cell including a container in contact with the anodeof a metal inert to the 10 electrolyte and having a low contactpotential with respect to zinc, the combination with said cathode bodyof a metal supporting rod extending through a generally axial channel insaid body, the diameter of said rod being smaller than that of saidchannel by an amount greater than the maximum radial expansion oi' saidbody thereby providing an interspace for accommodating such radialexpansion, and a pair of end contact caps force-fitted on the respectiveterminal regions of said supporting rod and holding said body undercompression therebetween and in permanent electrical conducting relationwith the rod whereby an velectrical contact of low resistance is mainl2tained between the cathode body and the said rod and deterioration andsplitting of the said bodyis positively prevented when isaid bodyexpands upon absorbing electrolyte.

SAMUEL RUBEN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 720,592 Kohn Feb. 17, 19031,137,226 Manchester Apr. 27, 1915 1,340,222 Graamans May 18, 19201,637,446 Hendry Aug. 2, 1927 2,221,106 Portail Nov. 12, 1940 2,233,593Eddy et al Mar. 4, 1941 2,379,374 Payne June 26, 1945 FOREIGN PATENTSNumber Country Date 195,580 Great Britain Oct. 12, 1923

1. A SEALED ALKALINE PRIMARY CELL COMPRISING, IN COMBINATION, AT LEASTONE GENERALLY CYLINDRICAL COHERENT CONDUCTIVE CATHODE BODY CONTAINING ANELECTROLYTICALLY REDUCIBLE OXYGEN-YIELDING COMPOUND AND HAVING AN AXIALCHANNEL THERETHROUGH, A TERMINAL ROD OF FERROUS METAL EXTENDING THROUGHSAID CHANNEL AND HAVING A DIAMETER WHICH IS SMALLER THAN THAT OF THECHANNEL, THE INNER SURFACE OF SAID CHANNEL DEFINING AN EXPANSION OF SAIDWITH SAID ROD FOR FREE RADIAL EXPANSION OF SAID CATHODE BODY, ANAPERTURED METAL CONTACT PLATE FORCE-FITTED ON EACH END OF SAID ROD INPRESSURE ENGAGEMENT WITH THE CORRESPONDING END FACE OF SAID CATHODE BODYTHEREBY HOLDING THE SAID BODY UNDER AXIAL COMPRESSION BUT RADIALLYSPACED FROM THE ROD, AN AMALGAMATED ZINC ANODE SURROUNDING SAID CATHODE,AN IMMOBILIZED BODY OF AN ALKALINE ELECTROLYTE INTERPOSED BETWEEN AND INCONTACT WITH SAID CATHODE AND ANODE, AND A CONTAINER OF A METAL SELECTEDFROM THE GROUP OF COPPER AND SILVER FOR SAID CELL SURROUNDING AND INCONTACT WITH SAID ANODE, THE QUANTITY OF ZINC BEING BALANCED WITH THEDEPOLARIZING CAPACITY OF THE CATHODE SO THAT BOTH ANODE AND CATHODE ARECONSUMED SUBSTANTIALLY SIMULTANEOUSLY.